2012-10-25 15:03:58: Created issue 'root container needs better definition' nickname owned by Mike Dolan on product Simple Delivery Profile for Closed Captions, description 'TTML defers the definition of the root container to the application. SDP-US is silent. For US captions, the root container must be registered with the related video. By remainig silent, then for example, one implementation could set the origin in the center of the video, or off-screen; or set the extent wildly off-screen. That would not have the a presentation result that meets the intent of this profile. So, we need to define the root contaner in terms of the related coded video (not the physical display which would be unknown to the author). A potential resolution would be to add something of the form: "The root container origin shall be the upper left corner of the related video coding; and the extent shall be the lower right corner."
' non-public [Mike Dolan]